To control a synthesizer from a stringed musical instrument such as a guitar, the frets of the guitar have to be detected. A conventional acoustic guitar has six strings, with each string vibrating at a frequency that is dependent on its length, its weight and its tension with respect to how it is secured to the guitar. The strings of the guitar are stretched out over what is known as a fingerboard (or fret board), with the latter having mounted or integrated thereon a plurality of spaced parallel frets. Thus, when a performer pushes his fingers down at a fret position, he in effect is tying that string against the fret, thereby shortening the string and therefore causing the string to vibrate at a higher frequency. The sound, or more precisely the pitch of the sound, obtained from each string is thereby controlled. In an electronic guitar, to determine the particular frequency of a string, which frequency is to be generated by a synthesizer in response to the signal generated from the string, the particular fret onto which the string is displaced in contact with needs to be read to determine the frequency the synthesizer is to generate.
Japanese Laid Open Patent Application No. 32708/78 discloses an electronic musical instrument which uses electrical resistance wires as strings to obtain changes of voltages or currents, in reference to the length of the resistance strings. In a specific embodiment, the Japanese reference teaches that a string may be pressed to a fret for completing an electrical circuit to generate an output voltage, which may then be amplified and converted into a frequency signal. Different frets may be contacted by the string to generate different signals. This Japanese reference, however, fails to take into consideration instances where the string may not be in direct contact with a fret or, due to unforeseen happenings--such as dirt or oxidation accumulating at the string--where the resistance of the string would be changed somewhat. This variation in frequency in turn would affect the accuracy of the frequencies generated.
It is, therefore, an objective of the present invention to provide for a method of reading the frets in a stringed electronic musical instrument so that frequencies which more accurately correspond to the frets in contact with the strings may be obtained.
It is another objective of the present invention to provide for a stringed electronic musical instrument that can be practiced with the above-mentioned advantageous method.
It is yet another objective of the present invention to provide at relatively low expense an electronic musical instrument that can generate frequencies reflecting accurately the frets on its fingerboard.
It is yet a further objective of the present invention to provide an electronic musical instrument using resistance strings which are arranged so as to obviate the undesirable effects of contact resistance.